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Stories in Stone

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Scientific Method

Salt Expirement

Purpose-
To tell the difference between rocks and minerals using the knowledge if it has a crystal structure.

Hypothesis-
We predicted that the water on the metal and plastic spoons and the cups, will evaporate the solution of hot water and salt that we put in it will evaporate and leave salt crystals, or halite deposits.

Materials-

• 8 cups (so the water won't leak)
• 2 spoons (we used one metal and one plastic)
• boiling water
• table salt
• stirrers
• tape
• a plastic plate

Procedure-
First, you stack up 4 cups into 2 groups, and pour 2/3 of a tablespoon of salt into the cup. Then, fill half the cup with boiling water and stir until the salt is dissolved. Then, tape one of the spoons on on side of the plate and tape the other one on the other side. Fill it up 3/4 or 1/2 of the cup with water.Add a pinch of salt. Wait one day, then observe what has become of the solution of the table salt and the hot water.

Data/Observations-

metal spoon observations	plastic spoon observations
has a crystal structure	has a crystal structure
has bigger crystals than plastic spoon	has smaller crystals than metal spoon
shaped into cubes	faded white color (transparent)

CER-
Our hypothesis was right, the solution that evaporated left salt crystals more informaly known as halite. We knew that it was a mineral becuase it was solid, and it had a cubed crystal structure.


As you can see, the crystal halite is shaped
like a cube, so its crystal structure is a cube.
( picture from http://www.chem.ox.ac.uk/icl/heyes/structure_of_solids/Scans/Halite(NaCl).JPG)

Rock Number	Properties	Prediction Rock/min	Why
1	rough,solid,shiny	mineral	because there are other minerals in it
2	rough,solid,shiny	rock	it's cleavage looks hard
3	split into cracks,shiny	mineral	it cracks easily
4	hard,solid,dull	mineral	it's hard
5	hard,solid,there are lots of different colors	rock	it has lots of other minerals in it
6	hard,pointy,smooth	rock	it is hard to break
7	light,shiny,rough	mineral	it is very light
8	rough,hard,solid	rock	it has lots of minerals in it
9	rough,hard,shells	rock	there are lots of minerals combined
10	rough,hard,solid	rock	it does not have a crystal structure
11	rough,hard,solid	rock	it has different minerals in it
12	smooth,solid	rock	it is hard to break
13	rough,shiny,crystal structure	mineral	it has a crystal structure
14	rocky,rough	rock	it has minerals in it
15	hard,rough,solid	rock	it has minerals in it
16	smooth,hard	rock	it is hard and solid